Increased p190RhoGEF expression in activated B cells correlates with the induction of the plasma cell differentiation

Previously, we demonstrated that the p190 Rho guanine nucleotide exchange factor (p190RhoGEF) was induced following CD40 stimulation of B cells. In this study, we examined whether p190RhoGEF and a downstream effector molecule RhoA are required for B cell differentiation. Expression of p190RhoGEF positively correlated with the expression of surface markers and transcriptional regulators that are characteristic of mature B cells with plasma cell (PC) phenotypes. Moreover, either the overexpression of p190RhoGEF or the expression of a constitutively active RhoA drove cellular differentiation toward PC phenotypes. B cell maturation was abrogated in cells that overexpressed p190RhoGEF and a dominant-negative form of RhoA simultaneously. CD40-mediated maturation events were also abrogated in cells that overexpressed either dominant-negative p190RhoGEF or RhoA. Together, these data provide evidence that p190RhoGEF signaling through RhoA in CD40-activated B cells drives the induction of the PC differentiation.

Ligation of CD40 receptor in human B lymphocytes triggers the 5-lipoxygenase pathway to produce reactive oxygen species and activate p38 MAPK

Previously, we reported that CD40-induced production of reactive oxygen species (ROS) by NADPH oxidase requires the TNF receptor-associated factor (TRAF) 3, as well as the activities of phosphatidylinositol 3-kinase (PI3K) and Rac1. Here we investigated the possible mechanisms of the production of ROS after CD40 ligation in B cells. We describe an alternative ROS production pathway that is triggered by CD40 ligation, involves 5-lipoxygenase (5-LO), and results in activation of p38 MAPK. Our studies in Raji human B lymphomas revealed that CD40-induced ROS production by 5-LO also requires the activities of PI3K and Rac1. In contrast to the NADPH oxidase pathway, however, TRAF molecules are not required for the CD40-induced ROS production by 5-LO. The association of CD40 with 5-LO is dependent on CD40 ligation in Raji B cells, and co-immunoprecipitation experiments using epitope-tagged proteins transiently expressed in human embryonic kidney 293T cells revealed the role of the regulatory subunit of PI3K, p85, in this association. Collectively, these data suggest a separate pathway for the CD40-induced ROS production in B cells and demonstrate that this pathway requires 5-LO via direct association of p85 with both CD40 and 5-LO.

Expression of Heme Oxygenase-2 and Smooth Muscle Relaxation by Carbon Monoxide in Rat Prostate: Effects of Age and Castration / 대한비뇨기과학회지

PURPOSE: Carbon monoxide (CO), as well as nitric oxide (NO), have been proposed as potential effectors in the non-adrenergic, non-cholinergic (NANC), nerve-mediated relaxation of the prostate. Attempts were made to determine the localization and expression of heme oxygenase-2 (HO-2), and to observe the change in the relaxation of the smooth muscle induced by CO, depending on age and castration, in rat prostate glands. MATERIALS AND METHODS: The prostate smooth muscles, isolated from young (125+/-4.5g, n=18), adult (321+/-17.8g, n=18), old (413+/-6.4g, n=18) and castrated adult (318+/-15.2g, n=18) rats, were used. The HO-2 immunohistochemistry was observed using the rabbit anti-HO-2 polyclonal antibody. The expressions of HO-2 were measured by a reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. Polygraphy, connecting the force displacement transducer, was used to observe the relaxation effect of CO. To investigate the relaxation action of the CO mediated, to the soluble guanylate cyclase (sGC) enzyme inhibitors, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and methylene blue were added to the reaction solutions. RESULTS: The HO-2 was located in the nerve fibers of the rat prostates. A quantitative analysis of PCR products revealed greater decreased levels of HO-2 mRNA and protein expression in the young (p<0.05) and castrated adults (p<0.05) than in the normal adult rats. The relaxation effect of CO was greater in the adult than in the young (p<0.05), old and castrated adult rats (p<0.05), but the effect was inhibited by the addition of ODQ and methylene blue in all groups (p<0.05). CONCLUSIONS: CO has an effect on the relaxation of rat prostate smooth muscle. The expression of HO-2 in the prostate became higher with increasing age, so it is estimated the relaxation effect of CO in the older adults will be higher than with the other ages. Androgen deprivation decreases relaxation effect of CO in prostate smooth muscle.

Comparative Study of Concentration of Isoflavones and Lignans in Plasma and Prostatic Tissues of Normal Control and Benign Prostatic Hyperplasia

Objective: Isoflavones and lignans are phytoestrogens that have recently gained interest as dietary factors related to prostatic diseases. However, no data on the concentrations in prostate tissue in humans is available. Therefore, the concentrations of isoflavones and lignans in plasma and prostatic tissues according to the prostate volume were compared to determine their possible effect on the benign prostatic growth. Methods: Fasting plasma and prostatic tissue specimens were acquired from 25 men over 50 years of age with similar normal dietary habits and no previous history of drug intake that could affect the isoflavones and lignans levels. The tissue was acquired either during a transurethral resection of the prostate in 15 patients with benign prostatic hyperplasia (BPH) with prostate volume over 40 ml or during a radical cystoprostatectomy in 10 patients with bladder cancer with a prostate volume < 25 ml, who were used as the controls. Quantitative analysis of the isoflavones, specifically equol, daidzein and genistein and lignans, particularly enterodiol and enterolactone, was performed by gas chromatography-mass spectrometry. Results: The mean prostatic concentrations of enterodiol, enterolactone, equol and daidzein in the BPH and the control groups were similar. However, the mean prostatic concentration of genistein was significantly lower in the BPH group than in the control group (65.43 +/- 17.05 vs 86.96 +/- 37.75 ng/ ml, respectively, p=0.032). The plasma concentration of isoflavones and lignans in the two groups were comparable. Conclusion: Isoflavones, but not lignans, have some influence the benign prostatic growth, and the prostatic concentration of genistein possibly has the closest association among them. More studies to further clarify the roles and mechanisms of isoflavone action on BPH including pharmacokinetic studies are recommended.

Changes in the Expression of Bone Morphogenetic Protein Receptor Type IA, IB and II in Human Prostate by the Suppression of Dihydrotestosterone / 대한비뇨기과학회지

PURPOSE: To investigate whether the expression of type IA, IB and II bone morphogenetic protein receptors (hBMPRs) are affected by the suppression of dihydrotestosterone (DHT) in the prostate tissues of patients with benign prostatic hyperplasia (BPH), we determined mRNA levels and protein expression patterns of the hBMPRs in human prostate tissues. MATERIALS AND METHODS: Frozen tissues were obtained during the transurethral resection of the prostate (TURP) in BPH patients who had taken the 5alpha-reductase inhibitor (finasteride), for 3 months prior to surgery, for the reduction of the prostate volume. Tissues from patients who had not taken finasteride prior to the TURP were used as controls. Patients over 50 years old, and with a prostate volume over 50ml, were included. Semiquantitative polymerase chain reaction (PCR) and immunoblotting were used to compare the expressions of the human bone morphogenetic protein receptors (hBMPRs) between the experimental group and the controls. RESULTS: All of the BMPRs proteins were expressed in the human benign prostate tissues, with various concentrations. The semiquantitative PCR analysis showed that the mRNA level of the hBMPRs tended to decrease following 5alpha-reductase inhibition, and the magnitude of this decrease was the greatest for the hBMPR-IB. CONCLUSIONS: In the human prostate, only the expression of hBMPR-IB was significantly reduced by the suppression of DHT. Further studies on the possible role of the hBMP-hBMPR-IB complex, in the abnormal proliferation of the prostate under physiological conditions, are warranted.